1. Field of Invention
The present invention relates to an inspection system for a variable valve lift device, and more particularly, to an inspection system for a continuous variable valve lift device, which measures and inspects valve lift values of a continuous variable valve lift device assembled in a vehicle engine assembly line.
2. Description of Related Art
In general, in an engine of a vehicle, a combustion chamber configured to generate power by combusting fuel is provided, and a valve train is provided which includes an intake valve, which controls an inflow of air, or a mixture of air and fuel which flows into the combustion chamber, and an exhaust valve which controls an outflow of exhaust gas discharged from the combustion chamber.
In addition, the combustion chamber is opened and closed while the intake and exhaust valves of the valve train are operated by a cam which is moved together with rotational motion of a crankshaft rotated by receiving power generated by the combustion of fuel.
As the cam is formed to have a predetermined profile, the intake and exhaust valves always have a predetermined lift value, and amounts of inflow and outflow of air and exhaust gas, which flow into and out of the combustion chamber through the intake and exhaust valves, are also set to be a predetermined amount in accordance with the lift value of the cam.
By the way, when the lift values of the intake and exhaust valves are appropriately adjusted in accordance with an operational state of an engine for a vehicle, fuel efficiency and output of the engine may be increased, and therefore a variable valve lift device configured to adjust the lift value of intake and exhaust valves in accordance with an operational state of the engine is being proposed.
A continuous variable valve lift device among the variable valve lift devices adjusts the lift value of the valve for each driving region of the engine in a range from 1 mm to 11 mm, thereby achieving an improvement in fuel efficiency of the engine, and an increase in output of the engine.
FIG. 1 illustrates an example of a six joint link type continuous variable valve lift device according to the related art, and an end of a valve 10, which opens and closes a combustion chamber provided in an engine of a vehicle, is connected to a swing arm 12, the swing arm 12 is installed at an upper portion of a cylinder head, which forms a combustion chamber and is not illustrated, to be rotatable about a pivot shaft 14, and a hydraulic lash adjuster (HLA) is connected to the other end of the swing arm 12.
The six joint link type continuous variable valve lift (CVVL) device is installed on an upper portion of the swing arm 12, and continuously varies a valve lift value of the valve 10 which reciprocates by the swing arm 12.
The six joint link type continuous variable valve lift (CVVL) device includes a control shaft 20 disposed at a center, an eccentric cam 22 mounted on the control shaft 20 to be integrally rotated with the control shaft 20, and a control link 24 fitted with an outer circumference of the eccentric cam 22.
In addition, the six joint link type continuous variable valve lift (CVVL) device includes an input link 26 disposed in a clockwise direction based on the control link 24 and having one end connected to the control link 24, an input rocker 28 connected to the other end of the input link 24 and mounted to be fitted with an outer circumference of the control shaft 20, an output link 30 disposed in a counterclockwise direction based on the control link 24 and having one end connected to the control link 24, and an output rocker 32 having one end connected to the other end of the output link 30 and mounted to be fitted with an outer circumference of the control shaft 20.
A roller 12a of the swing arm 12 is installed to be in contact with a lower end operating surface of the output rocker 32, and a roller 28a of the input rocker 28 is installed to be in close contact with a cam 40 which is rotated through a camshaft 40a. 
Accordingly, when the cam 40 is rotated by receiving rotational power of the engine, rotational motion of the cam 40 is inputted to the continuous variable valve lift (CVVL) device through the input rocker 28 and then transmitted to the swing arm 12 via the operating surface of the output rocker 32, and the swing arm 12 reciprocates the valve 10 while rotating.
When the valve lift is adjusted by the continuous variable valve lift (CVVL) device, the control shaft 20 is rotated in a clockwise direction by a control of a controller, which is not illustrated, the eccentric cam 22 is rotated by the rotational motion of the control shaft 20, and the output link 30 and the output rocker 32 are moved by the rotational motion of the eccentric cam 22, respectively, as indicated by the arrow.
When the output rocker 32 is moved toward the valve 10, a contact point between the lower end operating surface of the output rocker 32 and the roller 12a of the swing arm 12 is changed, thereby adjusting the valve lift value.
That is, the valve lift value of the valve may be continuously varied in accordance with a moving stroke of the output rocker 32.
The aforementioned continuous variable valve lift (CVVL) device is assembled in a vehicle engine assembly line. A cylinder block, a crankshaft, a piston, and a cylinder head are sequentially assembled in the engine assembly line, and the continuous variable valve lift device is assembled in a process of assembling the cylinder head.
As the continuous variable valve lift device includes a plurality of components, and the components are assembled, manufacturing tolerance of each of the components and assembly tolerance inevitably occur. The continuous variable valve lift device typically varies the valve lift value in a range from 1 mm to 11 mm. In a case in which the valve lift value is 1 mm, even when manufacturing tolerance or assembly tolerance is just about 10% (0.1 mm) thereof, an intake deviation amount of intake gas for each cylinder occurs to be 10% or more, and as a result, stalling of an engine may occur, or fuel efficiency may deteriorate, and exhaust gas may be degraded.
Therefore, manufacturing tolerance of each constituent component is preferentially measured and checked before the continuous variable valve lift device is assembled, and if the manufacturing tolerance occurs, a cap shim is mounted on a valve stem of the valve assembled to the swing arm so as to absorb the manufacturing tolerance.
However, if assembly tolerance inevitably occurs even after the continuous variable valve lift device is assembled, and the assembly tolerance is not appropriately solved, the aforementioned degradation in engine performance occurs, and therefore it is necessary to necessarily perform an inspection in the vehicle engine assembly line after the continuous variable valve lift device is assembled.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.